As well as general intellectual difficulties, children and adults with Down syndrome exhibit a number of specific information processing problems, some of which are associated with an atypical pattern of brain organization in these individuals. For example, compared to other children and adults of a similar mental age, persons with Down syndrome have difficulty performing sequential limb and oral movements on the basis of verbal direction. The position taken in this research program is that this problem is due to the functional dissociation of the cerebral areas responsible for speech perception and those responsible for movement organization. This research program has four interrelated objectives. The first is to develop a neurobehavioral index of cerebral organization in persons with Down syndrome that will reliably predict individual differences in verbal-motor performance. The protocol, which involves performing rapid limb and oral movements following the dichotic presentation of verbal stimuli, will be validated using the latest in brain-imaging technology. The second objective is to use the brain- imaging technology to extend the understanding of cerebral organization in persons with Down syndrome to visual-spatial function, visual- language function and visual and auditory attentional processes. The third objective involves studies to extend research on sequential oral and limb movements to movements involving the coordination of effectors with each other and with information from the environment. The final objective involves experiments conducted to determine if verbal-motor performance findings involving children and adults with Down syndrome generalize to perceptual-motor skill acquisition. Of interest is whether or not the neurobehavioral and neurophysiological indices of cerebral organization associated with the first two research objectives predict skill acquisition in different instructional and rehabilitation contexts.